Isotope Analysis Reveals Foraging Area Dichotomy for Atlantic Leatherback Turtles

Background: The leatherback turtle (Dermochelys coriacea) has undergone a dramatic decline over the last 25 years, and this is believed to be primarily the result of mortality associated with fisheries bycatch followed by egg and nesting female harvest. Atlantic leatherback turtles undertake long migrations across ocean basins from subtropical and tropical nesting beaches to productive frontal areas. Migration between two nesting seasons can last 2 or 3 years, a time period termed the remigration interval (RI). Recent satellite transmitter data revealed that Atlantic leatherbacks follow two major dispersion patterns after nesting season, through the North Gulf Stream area or more eastward across the North Equatorial Current. However, information on the whole RI is lacking, precluding the accurate identification of feeding areas where conservation measures may need to be applied. Methodology/Principal Findings: Using stable isotopes as dietary tracers we determined the characteristics of feeding grounds of leatherback females nesting in French Guiana. During migration, 3-year RI females differed from 2-year RI females in their isotope values, implying differences in their choice of feeding habitats (offshore vs. more coastal) and foraging latitude (North Atlantic vs. West African coasts, respectively). Egg-yolk and blood isotope values are correlated in nesting females, indicating that egg analysis is a useful tool for assessing isotope values in these turtles, including adults when not available. Conclusions/Significance: Our results complement previous data on turtle movements during the first year following the nesting season, integrating the diet consumed during the year before nesting. We suggest that the French Guiana leatherback population segregates into two distinct isotopic groupings, and highlight the urgent need to determine the feeding habitats of the turtle in the Atlantic in order to protect this species from incidental take by commercial fisheries. Our results also emphasize the use of eggs, a less-invasive sampling material than blood, to assess isotopic data and feeding habits for adult female leatherbacks

vertebrate scavenging communities

A scavenger is an animal that feeds on the carcass or remains of any dead animal which it did not participate in its killing. Scavenging is pervasive across the animal kingdom and almost all predator species use carrion to a certain extent in both terrestrial and aquatic ecosystems. There is a group of animals, the obligate scavengers, which rely (almost) entirely on carrion. Among vertebrates, only birds have evolved into obligate scavengers, namely vultures, which suggests that the costs of adaptation to obligate scavenging are high. Obligate and facultative scavengers exhibit a wide array of adaptations to locate and exploit carrion across systems, including inexpensive locomotion to find the unpredictable carrion on savannas, caching carrion in cold tundra or chemotaxis in aquatic systems. Traditionally viewed as an opportunistic process, particularly for facultative scavengers, carrion consumption by vertebrates often follows complex and structured patterns and is crucial in maintaining the stability and structure of food webs.Peer reviewe

Mangrove forest restoration and rehabilitation

We analyzed current best practices and recommendations used in the implementation of mangrove rehabilitation and restoration (R/R) projects in the Atlantic-East Pacific (AEP) and the Indo-West Pacific biogeographic regions during the last 20 years. Comprehensive literature and World Wide Web searches were performed identifying 90 sites around the world where R/R actions have been implemented. For each site, we analyzed the sources of damage/impact and classified the origin as natural (siltation, erosion, the direct and indirect effect of tropical storms or tsunamis) or anthropogenic (pollution, land use policies, overharvesting, aquaculture, altered hydrology and hydroperiod). In most cases, the causes of damage were a complex mixture associated to erosion, hydrological impairment, deforestation, siltation, and land conversion for aquaculture and other land uses. The area extension of mangrove sites undergoing restoration or just afforestation ranged from few square meters to several thousand hectares. Numerous projects were implemented without an underlying science-based approach and were often ill-prepared and unsuccessful. Although there is no “one-size-fits-all” solution to restore or rehabilitate mangrove wetlands, published studies (particularly peer reviewed) provide useful insights into designing R/R projects with clearly defined and prioritized management objectives based on a diagnostic of the source of damage/deterioration. A critical step is to develop a decision tree that serves as a guide to optimize the use of available funding in the development, implementation, and monitoring of R/R protocols to set clear objectives, goals and deadlines. These steps should be part of a robust research agenda based on sound ecological theory and reliable monitoring practices, including the participation of local communities. Any monitoring and reporting program should address spatial and temporal replication that explicitly includes reference sites near the target restoration site. The results of each R/R project, whether successful or not, should be published, as they are critical sources of data and information for further development of mangrove R/R practices and methods within the community of restoration ecology science. We urge the continental level implementation of guidelines to advance international initiatives aimed to protect and conserve one the most productive and threatened coastal ecosystems in the world.SCOPUS: ch.binfo:eu-repo/semantics/publishe